Configuration

Jekyll allows you to concoct your sites in any way you can dream up, and it’s thanks to the powerful and flexible configuration options that this is possible. These options can either be specified in a _config.yml file placed in your site’s root directory, or can be specified as flags for the jekyll executable in the terminal.

Configuration Settings

Global Configuration

The table below lists the available settings for Jekyll, and the various options (specified in the configuration file) and flags (specified on the command-line) that control them.

Destination folders are cleaned on site builds

The contents of <destination> are automatically cleaned, by default, when the site is built. Files or folders that are not created by your site will be removed. Some files could be retained by specifying them within the <keep_files> configuration directive.

Do not use an important location for <destination>; instead, use it as a staging area and copy files from there to your web server.

Build Command Options

Serve Command Options

In addition to the options below, the serve sub-command can accept any of the options for the build sub-command, which are then applied to the site build which occurs right before your site is served.

Do not use tabs in configuration files

This will either lead to parsing errors, or Jekyll will revert to the default settings. Use spaces instead.

Custom WEBrick Headers

You can provide custom headers for your site by adding them to _config.yml

# File: _config.yml
webrick:
  headers:
    My-Header: My-Value
    My-Other-Header: My-Other-Value

Defaults

We provide by default Content-Type and Cache-Control response headers: one dynamic in order to specify the nature of the data being served, the other static in order to disable caching so that you don’t have to fight with Chrome’s aggressive caching when you are in development mode.

Specifying a Jekyll environment at build time

In the build (or serve) arguments, you can specify a Jekyll environment and value. The build will then apply this value in any conditional statements in your content.

For example, suppose you set this conditional statement in your code:

{% if jekyll.environment == "production" %}
   {% include disqus.html %}
{% endif %}

When you build your Jekyll site, the content inside the if statement won’t be run unless you also specify a production environment in the build command, like this:

JEKYLL_ENV=production jekyll build

Specifying an environment value allows you to make certain content available only within specific environments.

The default value for JEKYLL_ENV is development. Therefore if you omit JEKYLL_ENV from the build arguments, the default value will be JEKYLL_ENV=development. Any content inside {% if jekyll.environment == "development" %} tags will automatically appear in the build.

Your environment values can be anything you want (not just development or production). Some elements you might want to hide in development environments include Disqus comment forms or Google Analytics. Conversely, you might want to expose an “Edit me in GitHub” button in a development environment but not include it in production environments.

By specifying the option in the build command, you avoid having to change values in your configuration files when moving from one environment to another.

Front Matter defaults

Using YAML Front Matter is one way that you can specify configuration in the pages and posts for your site. Setting things like a default layout, or customizing the title, or specifying a more precise date/time for the post can all be added to your page or post front matter.

Often times, you will find that you are repeating a lot of configuration options. Setting the same layout in each file, adding the same category - or categories - to a post, etc. You can even add custom variables like author names, which might be the same for the majority of posts on your blog.

Instead of repeating this configuration each time you create a new post or page, Jekyll provides a way to set these defaults in the site configuration. To do this, you can specify site-wide defaults using the defaults key in the _config.yml file in your project’s root directory.

The defaults key holds an array of scope/values pairs that define what defaults should be set for a particular file path, and optionally, a file type in that path.

Let’s say that you want to add a default layout to all pages and posts in your site. You would add this to your _config.yml file:

defaults:
  -
    scope:
      path: "" # an empty string here means all files in the project
    values:
      layout: "default"

Please stop and rerun `jekyll serve` command.

The _config.yml master configuration file contains global configurations and variable definitions that are read once at execution time. Changes made to _config.yml during automatic regeneration are not loaded until the next execution.

Note Data Files are included and reloaded during automatic regeneration.

Here, we are scoping the values to any file that exists in the path scope. Since the path is set as an empty string, it will apply to all files in your project. You probably don’t want to set a layout on every file in your project - like css files, for example - so you can also specify a type value under the scope key.

defaults:
  -
    scope:
      path: "" # an empty string here means all files in the project
      type: "posts" # previously `post` in Jekyll 2.2.
    values:
      layout: "default"

Now, this will only set the layout for files where the type is posts. The different types that are available to you are pages, posts, drafts or any collection in your site. While type is optional, you must specify a value for path when creating a scope/values pair.

As mentioned earlier, you can set multiple scope/values pairs for defaults.

defaults:
  -
    scope:
      path: ""
      type: "pages"
    values:
      layout: "my-site"
  -
    scope:
      path: "projects"
      type: "pages" # previously `page` in Jekyll 2.2.
    values:
      layout: "project" # overrides previous default layout
      author: "Mr. Hyde"

With these defaults, all pages would use the my-site layout. Any html files that exist in the projects/ folder will use the project layout, if it exists. Those files will also have the page.author liquid variable set to Mr. Hyde.

collections:
  my_collection:
    output: true

defaults:
  -
    scope:
      path: ""
      type: "my_collection" # a collection in your site, in plural form
    values:
      layout: "default"

In this example, the layout is set to default inside the collection with the name my_collection.

Glob patterns in Front Matter defaults

It is also possible to use glob patterns (currently limited to patterns that contain *) when matching defaults. For example, it is possible to set specific layout for each special-page.html in any subfolder of section folder.3.7.0

collections:
  my_collection:
    output: true

defaults:
  -
    scope:
      path: "section/*/special-page.html"
    values:
      layout: "specific-layout"

Globbing and Performance

Please note that globbing a path is known to have a negative effect on performance and is currently not optimized, especially on Windows. Globbing a path will increase your build times in proportion to the size of the associated collection directory.

Precedence

Jekyll will apply all of the configuration settings you specify in the defaults section of your _config.yml file. However, you can choose to override settings from other scope/values pair by specifying a more specific path for the scope.

You can see that in the second to last example above. First, we set the default page layout to my-site. Then, using a more specific path, we set the default layout for pages in the projects/ path to project. This can be done with any value that you would set in the page or post front matter.

Finally, if you set defaults in the site configuration by adding a defaults section to your _config.yml file, you can override those settings in a post or page file. All you need to do is specify the settings in the post or page front matter. For example:

# In _config.yml
...
defaults:
  -
    scope:
      path: "projects"
      type: "pages"
    values:
      layout: "project"
      author: "Mr. Hyde"
      category: "project"
...

# In projects/foo_project.md
---
author: "John Smith"
layout: "foobar"
---
The post text goes here...

The projects/foo_project.md would have the layout set to foobar instead of project and the author set to John Smith instead of Mr. Hyde when the site is built.

Default Configuration

Jekyll runs with the following configuration options by default. Alternative settings for these options can be explicitly specified in the configuration file or on the command-line.

There are two unsupported kramdown options

Please note that both remove_block_html_tags and remove_span_html_tags are currently unsupported in Jekyll due to the fact that they are not included within the kramdown HTML converter.

# Where things are
source:          .
destination:     ./_site
collections_dir: .
plugins_dir:     _plugins
layouts_dir:     _layouts
data_dir:        _data
includes_dir:    _includes
collections:
  posts:
    output:   true

# Handling Reading
safe:                 false
include:              [".htaccess"]
exclude:              ["Gemfile", "Gemfile.lock", "node_modules", "vendor/bundle/", "vendor/cache/", "vendor/gems/", "vendor/ruby/"]
keep_files:           [".git", ".svn"]
encoding:             "utf-8"
markdown_ext:         "markdown,mkdown,mkdn,mkd,md"
strict_front_matter: false

# Filtering Content
show_drafts: null
limit_posts: 0
future:      false
unpublished: false

# Plugins
whitelist: []
plugins:   []

# Conversion
markdown:    kramdown
highlighter: rouge
lsi:         false
excerpt_separator: "\n\n"
incremental: false

# Serving
detach:  false
port:    4000
host:    127.0.0.1
baseurl: "" # does not include hostname
show_dir_listing: false

# Outputting
permalink:     date
paginate_path: /page:num
timezone:      null

quiet:    false
verbose:  false
defaults: []

liquid:
  error_mode: warn

# Markdown Processors
rdiscount:
  extensions: []

redcarpet:
  extensions: []

kramdown:
  auto_ids:       true
  entity_output:  as_char
  toc_levels:     1..6
  smart_quotes:   lsquo,rsquo,ldquo,rdquo
  input:          GFM
  hard_wrap:      false
  footnote_nr:    1
  show_warnings:  false

Liquid Options

Liquid’s response to errors can be configured by setting error_mode. The options are

• lax — Ignore all errors.
• warn — Output a warning on the console for each error.
• strict — Output an error message and stop the build.

Markdown Options

The various Markdown renderers supported by Jekyll sometimes have extra options available.

Redcarpet

Redcarpet can be configured by providing an extensions sub-setting, whose value should be an array of strings. Each string should be the name of one of the Redcarpet::Markdown class’s extensions; if present in the array, it will set the corresponding extension to true.

Jekyll handles two special Redcarpet extensions:

• no_fenced_code_blocks — By default, Jekyll sets the fenced_code_blocks extension (for delimiting code blocks with triple tildes or triple backticks) to true, probably because GitHub’s eager adoption of them is starting to make them inescapable. Redcarpet’s normal fenced_code_blocks extension is inert when used with Jekyll; instead, you can use this inverted version of the extension for disabling fenced code.

Note that you can also specify a language for highlighting after the first delimiter:

    ```ruby
    # ...ruby code
    ```

With both fenced code blocks and highlighter enabled, this will statically highlight the code; without any syntax highlighter, it will add a class="LANGUAGE" attribute to the <code> element, which can be used as a hint by various JavaScript code highlighting libraries.

• smart — This pseudo-extension turns on SmartyPants, which converts straight quotes to curly quotes and runs of hyphens to em (---) and en (--) dashes.

All other extensions retain their usual names from Redcarpet, and no renderer options aside from smart can be specified in Jekyll. A list of available extensions can be found in the Redcarpet README file. Make sure you’re looking at the README for the right version of Redcarpet: Jekyll currently uses v3.2.x. The most commonly used extensions are:

• tables
• no_intra_emphasis
• autolink

Custom Markdown Processors

If you’re interested in creating a custom markdown processor, you’re in luck! Create a new class in the Jekyll::Converters::Markdown namespace:

class Jekyll::Converters::Markdown::MyCustomProcessor
  def initialize(config)
    require 'funky_markdown'
    @config = config
  rescue LoadError
    STDERR.puts 'You are missing a library required for Markdown. Please run:'
    STDERR.puts '  $ [sudo] gem install funky_markdown'
    raise FatalException.new("Missing dependency: funky_markdown")
  end

  def convert(content)
    ::FunkyMarkdown.new(content).convert
  end
end

Once you’ve created your class and have it properly set up either as a plugin in the _plugins folder or as a gem, specify it in your _config.yml:

markdown: MyCustomProcessor

Incremental Regeneration

Incremental regeneration is still an experimental feature

While incremental regeneration will work for the most common cases, it will not work correctly in every scenario. Please be extremely cautious when using the feature, and report any problems not listed below by opening an issue on GitHub.

Incremental regeneration helps shorten build times by only generating documents and pages that were updated since the previous build. It does this by keeping track of both file modification times and inter-document dependencies in the .jekyll-metadata file.

Under the current implementation, incremental regeneration will only generate a document or page if either it, or one of its dependencies, is modified. Currently, the only types of dependencies tracked are includes (using the {% include %} tag) and layouts. This means that plain references to other documents (for example, the common case of iterating over site.posts in a post listings page) will not be detected as a dependency.

To remedy some of these shortfalls, putting regenerate: true in the front-matter of a document will force Jekyll to regenerate it regardless of whether it has been modified. Note that this will generate the specified document only; references to other documents’ contents will not work since they won’t be re-rendered.

Incremental regeneration can be enabled via the --incremental flag (-I for short) from the command-line or by setting incremental: true in your configuration file.